Start Updating portage cache

Updating portage cache

You can think of each as a mini Linux system, although they start off with hardly any packages installed.

For example, if a package supports creating optional perl bindings, then it can declare a perl USE flag.

If "-perl" is specified then the package can omit creation of the bindings and drop its dependency on perl.

These are only used for compilation and will not be placed into images that are built via build_image.